Wow, sorry, I said it clumsily. I mentioned Europe because Holly is from the States and she can have plenty from there (ain't I smart!!). She will get photos with the Flat Stanley from Africa too. Wouldn't know about Asia and other continents. In any case, all places on this planet are equally interesting, of course!
As for the size of the photo. Hm, the Flat Stanley should be clearly visible and his size shouldn't be smaller than A4. The photo with Stanley should be of the size which can be printed and displayed for other people to see.
Sayonara
P.S. Holly drew this, so even if she did it based on a picture from a book it is still Holly's interpretation and her artistic skills.